The present invention relates to a speed measuring device and more particularly to a device for determining various speed parameters of a jet engine such as determining time required to reach a percentage of nominal design speed, time to accelerate from idle to a desired speed and time to decelerate from full throttle speed to a desired speed.
Various measuring devices are employed for determining or detecting the speed of a mechanical element, particularly a rotating element. For example, in U.S. Pat. No. 4,028,686, entitled, "Digital Detector", which issued June 7, 1977, to Michael A. Wilson and Gordon E. Gee, a device is provided for measuring the speed of each driver wheel of a truck and comparing the speeds electronically to denote a skidding condition of a vehicle.
Another speed measuring system is described in U.S. Pat. No. 3,886,406, which issued May 27, 1975, to Robert F. Anderson. This system is used to detect an overspeed condition and uses a tachometer which generates a frequency comparable to vehicle speed. A detector relay is energized if the frequency generated by the tachometer becomes above the frequency of a high-pass filter.